Re: [cf-pointobsconvention] Should Z Coordinates be required?

John Caron wrote:
It seems like there are 2 use cases people have in mind:

1. A data provider is using this Convention to write out data. Presumably the provider is working hard to put quality metadata into their files. I'd really like to encourage (require?) them to put in time, z, x, and y geolocation information. Is there really a case where that information is not available at the raw data writing?

2. Middleware software is using this Convention as an exchange format, ie rewriting original data into this format. Here, its quite possible that the z coordinate in particular is missing.

The work that our group does falls into this category. I don't know of any point observation data we have that either does not have the z-coordinate specified or can be known from associated documentation. The hurricane track data that was previously mentioned, for example, does not explicitly include the z-coordinate, but the format documentation states that the wind and pressure are valid at the surface, so the z-coordinate can be specified during the translation from native format to CF-compliant netCDF. My opinion is that option 4 is the way to go, with the ability to specify "unknown" if z is really not known, but at least data users will know that it wasn't unintentionally omitted, and data providers and translators will maybe be prodded to work a little harder to include it.

Bob Dattore
Software Engineer/Programmer
UCAR/NCAR/CISL/Data Support Section
Phone: (303) 497-1825
Email: dattore@xxxxxxxx
Web: http://dss.ucar.edu